1. Field of the Invention
The present invention generally relates to a watercraft with a propulsion device and an engine, and more particularly relates to control circuits and methods for controlling the throttle and shift mode settings of an engine.
2. Description of Related Art
Computerized controls have become popular in recent years for watercrafts. In one arrangement of the watercrafts, a propulsion device propels the watercraft and an engine powers the propulsion device. A remote controller and a control device are provided to remotely control the propulsion device and the engine. For instance, some of such computerized controls are disclosed in U.S. Pat. No. 6,431,930 (corresponding to JP2000-108995) and JP2000-313398.
In a typical example, an outboard motor incorporates the propulsion device and the engine. The propulsion device of the outboard motor can be, for example, a propeller that is rotatably coupled with a crankshaft of the engine through a driveshaft and a propeller shaft. The outboard motor can have a changeover mechanism that changes the propeller among forward, neutral and reverse modes. The watercraft proceeds forwardly when the propeller is in the forward mode and rotates in a right direction, and proceeds backwardly when the propeller is in the reverse mode and rotates in a reverse direction. The watercraft is not propelled when the propeller is in the neutral mode and does not rotate.
The engine of the outboard motor can be provided with an air intake device that introduces air to a combustion chamber of the engine. The intake device can have a throttle valve that moves between a fully closed position and a fully open position to regulates an amount of the air. The intake device introduces a relatively small amount of air when the throttle valve is in the fully closed position or adjacent to the fully closed position, while the intake device introduces a relatively large amount of air when the throttle valve is in the fully open position or adjacent to the fully open position.
The remote controller is operable by an operator so as to input a desired mode of the propeller and a desired throttle valve position to the control device. The control device can control the changeover mechanism and the throttle valve position by actuators based upon the desired mode and the desired throttle valve position, respectively.
In the conventional controls, however, an abnormal mode change or a discomfort shock can occur.